Plaster board



Oct. 26 1926.

' C. E. MEHLHOPE PLASTER BOARD Fil-od May 28l A3,921

faz/@Ziff Patented oer. 26, 1926- UNITED STATES PATENT OFFICE.4

CLARENCE E. MEI-ILHOPE, 0F WINNETKA, ILLINOIS, ASSIGNOR, BY MESITTIEI ASSIGN- MENTS, TO UNITED-STATES GYPSUM COMPANY.

PLASTER BOARD.

Application ledMay 28, 1921. Sei'ialNo. 473,288.

tended to supply aform of plaster board in which the top, bottom and edge faces are strongly protected by a vsubstantially continuous covering, While leaving the body, of

' plaster or similar material, homogeneous and without material points of weakness.

One illustrative embodiment of the invention is shown in the drawings, in which Fig.

v 1, drawn on a small scale, is a top face view y material on the other face.

of a strip of plaster board; and Fig. 2 drawn on a larger scale, is a transverse section on the .line 2, 2 of Fig. 1.

Fig.v2 shows the body 3 of plaster or the like having on one face a cover sheet 4 preferably of fibrous material such as' heavy paper, and having a cover sheet 5 of like The cover sheets 4 and 5 are so associated that collectively they supply a .practically continuous envelope encircling the top, bottom and edge faces of the plaster body. For instance, in the illustrative formthe coversheet 4 is folded over the body edges, and the -Inar- .gins '6 overlie the top 'face of the plasterl body; the top cover sheet 5 is applied to l the top face of the plaster body, and interposed between the edges of the bottom-sheet margins 6, 6. As shown, the sheets 4 and 5 do not overlap in any sense. On thev contrary, their adjacent edges, wherever located, are preferably butt-jointed as nearly as practicable -in ordinary commercial operations, so as to render the enveloping of the plaster body by the cover sheets, as completely continuous as desired.

lVhatever joints occur between the edges of the cover sheets are etectually sealed by sealing strips 7, 7 formed of thin and tough material overlaping and securely cemented to-'the adjacent cover-sheet margins at each joint. For example, after the cover sheets tegral and continuous encircling envelope.

The material of the sealing strips is preferred to be of a tensile strength equal to or greater than that of the cover material in the sheets 4 and 5. r

Referring to Fig. 2, the sheets 5 and 6 practically mergeinto each other and are strongly sealed together by the glued or cemented strips 7 which are adhered to the covering sheets independenly of the plaster body.' The sealing strips 7 7 being secured 1n place by a glue or cement of the highest efficiency, the sealing strip is in eiect, an integral part of each covering-sheet margin to which it is attached, and hence those marl gins function as though they were intergal with each other. At the same time, the sealing strips 7, although very tough and strong, are so thin, and are so securely glued in place, that the opportunity to tear or pry up their edges is minimized.y

Y The illustrative plaster board may4 be made in any appropriate manner. For instance, a bottom cover sheet may be fed past a chute which delivers plaster on'the upper 75 face thereof, after which the margins of the bottom sheet may be progressively folded upwardly and inwardly to embrace theedges of the plaster body; thereafter the top sheet 5 may be applied in position between the so edges of the inturned margins of the bottom' sheet. The substantially continuous envelope of cover sheet having been applied, the

sealing strips may be glued or cemented in to be included Within the sub-joined claims. are assembled with theplaster body,

1. lA composite boardccrnprising, in combination, a plaster body; substantially con' t-inuous fibrous cover material enveloping the body; and relatively thin, tough sheet -material and an adhesivel substantially stronger than said plaster. forsealing portions of said Covering material together to complete its' Continuity. A

Q.- 'A composite board or the like eomprising, in combination; `a plaster body; a bottom cover sheet having its margins folded over the bodyedges and inturned onto the top face-ot' the body; a top covering-sheet interposed between the edges of the inturned margins of the bottom sheet and lying in substantiallyv the saine plane therewith; and

. means for sealing said margins together ingins of the bottom sheet; and relatively thin, tough sealing stripsI glued or cemented to the respective covering-sheet margins to seal them together.

l. A composite board orthe like eoinpris- I ing, in combination, al substantially rigid plaster body; a bottomv cover sheet applied to one face of the body; a top cover vsheet applied to the opposite face of the body, said sheets having their edges Contiguous but not overlapping 5. and relatively thin sealing strips, of tensile strength at least lequal to l that of the cover sheet material, sealing together the contiguous edges ot' sheets.

In testimonywhereof, I have signedv my name to this specification. l. f

CLARENCE E. MEHLHOPE.

the cover 

